(a) Field of the Invention
The present invention relates to a zoom lens system, more particularly to a zoom lens system for a single lens reflex camera capable of compensating a change of an introversive coma at a telephoto position.
(b) Description of the Related Art
A conventional zoom lens system for a single lens reflex camera includes a first lens group of a positive refractive power which is movable toward an object along an optical axis for a magnification change, a second lens group of a negative refractive power which is fixed, a third lens group of a positive refractive power compensating an image plane when changing a magnification, and a fourth lens group of a negative refractive power which is movable toward an object as the first lens group moves for a magnification change.
However, the conventional zoom lens system with four lens groups has a problem of an introversive coma at a telephoto position, where an off-axis aberration varies greatly because an exit angle of an incident light beam entering the lens at an arbitrary angle changes as the fourth lens group moves.